She could have trapped gas, or sometimes it's something you ate that makes them fussy. My daughter had puked a couple of times after eating and then she was fine after, but just make you always try and burp her .
If she arches her back she may have reflux, maybe your pediatrician can give you some samples if a different formula for her-
If she's in pain you could also try a warm bath, I know they don't recommend Tylenol because they're so young still.
If that doesn't work, if you have a vibrating machine that'll soothe her , it always seemed to help my daughter when she wasn't comfortable in my arms
It's pretty common for her age to spit up a ton like almost as much as they ate. @momma_meg, does she burp good? Do u BF? Does she tighten her legs or make them straight after eating?